Assessment of obstetric history and cervical length as risk factors for preterm birth

Abstract

Introduction: Preterm birth, before 37 weeks of gestation, is the main determinant of neonatal morbidity and mortality and is associated with serious consequences,including compromised quality of life for the affected individual and physical, psychological, and economic costs. Objective: To evaluate the correlation of obstetric history, cervicovaginal infections, and cervical length with preterm birth. A prospective, blind cohort study evaluated 1,370 pregnant women from Ribeirão Preto between 20 and 25 weeks of gestation. Materials and methods: The correlation between obstetric history, cervical length, and gestational age at birth was obtained by calculating the relative risk of the different variables. Results: The distribution of pregnant women according to cervical length (CL) showed a predominance of women with a cervix longer than 2.5 cm (n = 1,308, 95.8%), followed by women with a cervix between 2 and 2.49 cm (n = 42, 3.1%) and < 2 cm (n = 15, 1.1%). Among the 1,370 pregnant women evaluated, 133 had spontaneous preterm birth (< 259 days); 14 (10.5%) preterm births occurred in women under 19 years of age, 105 (79%) in women between 19 and 35 years, and 14 (10.5%) in women older than 35 years. Microbiological analysis showed the growth of Mycoplasma hominis, Ureaplasma urealyticum, and other bacteria in 8, 17, and 16 women with preterm birth, respectively. Among the 133 women with spontaneous preterm birth, CL was < 2.5 cm in 15 women, < 2 cm in 3, < 1.5 cm in 3, and < 1 cm in 2. Conclusion: The identification of pregnant women at high risk for preterm delivery can reduce the incidence of preterm birth. Although no gold standard test exists for the prediction of preterm birth, this study confirms that the measurement of CL is a good individual predictor.

Keywords

• Obstetric history, Cervicovaginal infections, Cervical length, Preterm birth risk factors.